(1) Field of the Invention
This invention relates to roofing materials and, more particularly, to conductive roofing materials molded of conductive loaded resin-based materials comprising micron conductive powders, micron conductive fibers, or a combination thereof, substantially homogenized within a base resin when molded. This manufacturing process yields a conductive part or material usable within the EMF or electronic spectrum(s).
(2) Description of the Prior Art
Buildings of any kind require a roof, or roofing system, to protect building contents from the environment. The roof, itself, requires a covering material capable of shedding water. Residential roofing systems generally include three-tab shingles as one of the primary roof protection materials and are the roofing industry's current standard. Three-tab shingles consist of two layers of asphalt around a felt or fiberglass mat core covered with ceramic mineral granules. The shingles are typically notched into three integrated pieces, or tabs. On shallow pitched, or flat, roofs an asphalted felt or a fiberglass rolled roofing is the common protection material. Alternately, a synthetic rubber or a special Polyvinyl Chloride (PVC) plastic sheet is becoming more common for the flat or shallow pitched roof.
In commercial structures, in particular metal buildings, a standing seam metal roof is frequently used. A standing seam metal roof is constructed of interlocking metal panels that run vertically from the roof's ridge (the top of the roof) to the eave. The interlocking seam where two panels join together is raised above the roof's flat surface, allowing water to run off without seeping between metal panels. Other common types of roofing materials are ceramic or concrete tiles. These tiles are assembled to provide a waterproof and fireproof roof.
Shedding of water, or precipitation, is not the only consideration in roofing material applications. Other considerations include dealing with lighting, electromagnetic energy, heat build-up, and corrosion. Buildings that are in locations that are subject to lighting strikes, may need to provide lighting arrestors to allow any charge accumulated during a thunderstorm to be dissipated from the vicinity of the building without damaging the building. Most roofing materials, such as prior art shingles and roofing tiles, are good insulators. Therefore, these materials do not typically provide a path for dissipation of electrical charge as it accumulates. Metal roofs are inherently conductive. However, due to the desire to prevent corrosion, most metal roofing materials are coated or painted as a rust inhibitor. These coatings are typically insulating and thus reduce the ability to dissipate electrical charge or to prevent a lightening strike.
Several prior art inventions relate to roofing materials. U.S. Patent Publication U.S. 2002/0043044 A1 to Foster et al teaches a method of shingle composition that utilizes a rubber component in the range from about 5–95% by weight and a polyolefin component in the range of about 5–50% by weight. This invention teaches that the weight of this shingle to be less than 150 pounds per roofing square for ⅛ inch thickness as compared to typical asphalt shingles weighing 185 pounds per roofing square of the same thickness. U.S. Patent Publication U.S. 2002/0095901 A1 to Tremblay teaches a metal roofing shingle comprising a flat rectangular panel made of metallic sheet material. U.S. Patent Publication U.S. 2004/0241476 A1 to Friedman et al teaches a synthetic roofing shingle or tile that utilizes a core of recycled inexpensive materials with an outer skin material of greater quality and weather resistance. U.S. Patent Publication U.S. 2003/0054148 A1 to Jolitz teaches a composite roofing shingle that comprises about 35–65% polyethylene and 50–70% crushed limestone filler. U.S. Patent Publication U.S. 2002/0189188 A1 to Iole et al teaches a roofing system for buildings with synthetic resin molded components formed of entirely recyclable material. U.S. Patent Publication U.S. 2002/0152697 A1 to Hokkirigawa et al teaches a roofing tile and snow-melting, tiled roof using the same. This invention utilizes a fire resistant ceramic tile with an embedded nichrome wire for a resistive heat element. U.S. Patent Publication U.S. 2004/0074164 A1 to Behrens teaches a high frequency reducing green roofing that utilizes a layer of textile fibers, a vegetation layer, and a flat or three-dimensional structure of electrically conductive filaments. U.S. Patent Publication U.S. 2002/0180077 A1 to Glatkowski et al teaches a carbon nanotube fiber-reinforced composite structure for electromagnetic and lightning strike protection. This invention utilizes electrically conductive carbon nanotubes to act as the conductive filler.